Jusse Saros
Like Sorokin, Saros is likely one of the NHL's five most talented goalies.
The reason you don't want to swap Marner for a goalie is because the goalie is so unpredictable. If healthy, Marner will continue to score at a 100 piont pace and provide top-level defense.
Saros or Sorokin could be the next Andrei Vasilevskiy or they could play like they did this past year. Hard to know for sure, which is why elite forwards rarely get traded for a goalie, even though an elite goalie is far more important.
If the Leafs want Sorokin, he's going to cost Marner. If the Leafs want Saros, he might not. Saros is playing in front of one of the best goalie prospects in the world, and is due for a massive pay increase the cheap Nashville Predators might not be down with.
I could see the Leafs potentially putting together a package that doesn't include Marner that brings Saros to Toronto.
Either way, I can't stress this enough: pairing an elite goalie with Auston Matthews is a no-lose proposition. It's about the only thing the Leafs haven't tried, and it's about time.
That is why Saros and Sorokin are my 1A and 1B trade targets this off-season.
Saros is of course, about 100x more realistic.